Is programming against interfaces in Java the same concept as using header files in C/C++?

Question

The java code I\'m working on at the moment has often a structure like

file Controller.java:

interface Controller {...}

file Controller

Answer 1

The question is good, there is a connection between header files and classes/interfaces/OO programming, beyond the raw syntax of the languages.

Proper C++ program design:

• Put one class declaration, and one only, in a h-file.
• Give said h-file the same name as the class declared.
• Put the class definition in a cpp-file with the same name as the h-file.

Proper Java program design:

• Same as for C++, though also put interfaces in files of their own.

Proper C design:

• In the h-file, declare functions belonging to a particular "code module".
• Put the function definitions in a c-file with the same name as the h-file.
• All variables you would have declared as private/protected if writing C++/Java should either be truly private through the concept of "opaque type/pointers", or be placed at file scope and declared static, so that they can be shared between functions within the "code module" (though that makes the code non-reentrant).

If you don't use the above intimate connection between classes and h-files, there is a fine chance that your program is an unreadable mess, no matter how elegant your OO design is.